Multiple centers have applied 3D printing to create physical models designed from patients' imaging to be utilized by the treating team for preoperative planning. While the current practice is adequate for surgical planning, none of the available printed polymers have the ability to reproduce tissue properties permitting dissection, hemostasis and suturing. The emphasis of this proposal is to develop a truly immersive, realistic simulation platform for practicing surgeons, thus increasing the likelihood of skills transfer from the rehearsal to the live case. This project will develop and validate the technique of combining image segmentation, 3D printing and hydrogel molding technologies to fabricate realistic, functional and anatomically accurate patient-specific organ phantoms from patients' imaging to be utilized as a preoperative surgical rehearsal platform for renal cancer surgeries. Our underlying hypothesis is that by providing surgeons with a high-fidelity, patient-specific, simulation platform in which they can visually and physically interact, they will be able to plan and then rehearse a patient's procedure with sufficient immersion so that performing the actual procedure will feel familiar and can be performed with confidence and precision. Proving this hypothesis will focus on three essential aspects including 1) determining hydrogel polymer specifications that would replicate the physical properties of parenchymal cadaveric kidney tissue as well as renal vasculature. Tests include an unconfined compression, indentation and uniaxial tensile strength testing. Dual parameter optimization using an inverse finite element model (FEA) will enable determination of both Young's modulus (E) and Poisson's ratio (?) for each individual kidney component, 2) ensuring the anatomical accuracy of the fabricated kidney phantoms by comparing the anatomical accuracy of patient-specific kidney hydrogels to patients' original imaging. Scanning and segmentation of the models will generate a duplicate computer design of the patient's imaging that can be overlaid with the patient's original computer design generated from their medical imaging to provide a quantitative difference error for each structure (parenchyma, tumor, arterial, venous and urinary systems). In achieving these first two aims we will have the capability to create cost- effective patient-specific kidney phantoms that accurately represent the anatomical, physical, functional (bleeding) and radiological properties of each patient. Incorporating the essential surrounding organs would replicate all elements of kidney cancer surgery within a single immersive simulation platform. Finally, our third aim will be to assess the feasibility, realism and validity of our patient-specific surgical rehearsal environment for use in kidney cancer surgery by study of i) subjective surgical realism by expert urologists, and ii) ability to generate valid metrics of operative performance (blood loss, ischemia time, tumor size and tumor margins) that positively correlate to live surgery for the same patient .